The invention relates to a combined current and voltage measuring apparatus with a cast resin body which supports the current measuring unit and is also utilized as dielectric for the capacitor on the high-voltage side of the capacitive voltage divider equipped with an amplifier of a capacitive measuring unit. The cast resin body is penetrated by the primary conductor carrying the current to be measured.
A combined current and voltage transformer is known from Deutsche Auslegeschrift No. 1,114,921 wherein the voltage transformer unit contains a capacitive transformer. The dielectric of the winding insulation of the current transformer unit is also utilized as dielectric for the capacitor on the high-voltage side of the capacitive divider in that there are applied to the winding insulation conducting coatings forming the electrodes of the high-voltage capacitor.
The construction of this known combined current and voltage transformer leaves something to be desired inasmuch as it is relatively bulky; this is attributable to the fact that a relatively large current measuring unit in the form of a secondary winding with iron core is used which leads, in turn, to a correspondingly large cast resin body. This causes relatively high production costs and imparts a comparatively high weight to the known combination transformer on the one hand, and two coatings further increase cost on the other.
Accordingly, it is an object of the invention to provide a combined current and voltage measuring apparatus which affords a production cost advantage as well as an advantage in structural size when compared to the above-mentioned arrangement.